2018 VCE Computing: Software Development examination report · Development examination report General comments The 2018 VCE Computing: Software Development examination comprised three
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The table below indicates the percentage of students who chose each option. The correct
answer is indicated by shading.
Question % A % B % C % D Comments
1 1 88 9 2
2 32 19 32 17
Many students selected use case diagrams to be drawn as an example of a non-functional requirement. However, a non-functional requirement describes the attributes the solution should possess. Option C, which states that online ordering must be available 24 hours a day, seven days a week, does this.
3 1 10 69 20
4 13 67 15 5
5 26 65 7 2
6 5 10 17 68
7 61 15 13 10
8 6 12 74 7
9 3 1 6 90
10 83 9 6 2
11 8 14 61 17
12 8 14 30 47
Many students selected existence check as the validation check. Existence checks are used to see if data is entered, not if data exists in a list. Option C, range check, is the validation technique used to check against a list of valid ID numbers.
13 29 24 23 24
Option A is the only answer that satisfies the collection of solicited personal information. The personal information collected is used for, or is directly related to, the organisation’s activities.
14 61 2 33 4
15 7 62 2 29
16 11 63 9 17
17 21 15 62 2
18 80 5 3 13
19 47 27 1 25
Many students selected the Spam Act, however, as the organisation shared private data it may be
breaching the Privacy Act.
20 2 36 61 1
Section B – Short-answer questions
Question 1
Marks 0 1 2 3 Average
% 54 20 7 19 0.9
A trace table is a technique for checking that a module meets design specifications. It simulates
the execution of the module; as each statement is executed the variables change and this data is
recorded in a table. Many students had limited knowledge of this technique. Students should be
able to construct a table with appropriate variables/conditions/output/input headings and be able to
record data as they step through the algorithm.
Below is a possible response.
Classsize Count Sum Avemark WHILE loop
3 0 0 0 T
1 52 0 T
2 141 0 T
3 162 0 F
162/3=54
Question 2a.
Marks 0 1 2 Average
% 44 40 16 0.8
Many students found difficulty in providing an explanation of why reading from RAM could improve
the performance of the software application. This question, which asked students to ‘explain’,
required a consideration of cause and effect. For example, if ‘quicker access’ was stated as the
reason performance could be improved, details about access speed compared to hard disks was
required.
The following is an example of a high-scoring response.
Random Access Memory has faster read and write speeds than permanent storage (hard disk). This means that the software app will be able to search the records faster, improving its efficiency.
Question 2b.
Marks 0 1 2 Average
% 43 35 22 0.8
Most students were able to make a comment that there would be some compatibility issues if the
number of fields changes. However, many did not explain why there might be issues or explain if
coding also changed that data would be fully accessible.
The following is an example of a high-scoring response.
If the number of fields changes, certain elements/values may be processed by the wrong section of the program, causing type errors or other errors. Eg The postcode may be processed as a phone number.
Question 2ci.
Marks 0 1 2 Average
% 21 30 49 1.3
Many students showed some understanding of these data types but struggled to express the key
characteristics clearly and accurately. There were a number of possible responses; however, many
responded with a collection of individual characters (ASCII) and a whole number that could be
used in mathematical calculations, as the key characteristics for string and integer.
Students generally selected string as the most appropriate data type due to the possibility of
brackets or spaces in the variable.
Question 3
Marks 0 1 2 3 Average
% 50 28 16 5 0.8
Many students found this question difficult. Students needed to be able to describe an associative
array, outline how it is used and explain why a one-dimensional array was not appropriate in this
circumstance.
The following are two examples of high-scoring responses.
Example 1
An associative array contains a key and value. In this case the staff member’s name would be the value and the key would be the title of the report. Using an associative array means that staff will be able to search for who has borrowed the report since each report is assigned a value (staff member’s name). This option is better than a one-dimensional array since there are two categories needed to be recorded, the staff name and the report title, which a one-dimensional array cannot do.
Example 2
An associative array allows for two values to be paired, and lookups to be performed based on one specific value (in this case, the report title). If the data were to be stored in a one-dimensional array, it would not be possible to link reports with the staff member’s names. Additionally, associative arrays allow for many reports to be assigned to a single name, which is required for the solution.
Question 4
Marks 0 1 2 3 Average
% 20 23 37 20 1.6
A more efficient searching technique would be a binary search on sorted data. The study design
only specifies linear and binary searching. Students needed to identify binary search (using sorted
data), describe how the search technique works (list is repetitively halved) and why this was more
efficient than a linear search (fewer comparisons). Higher-scoring responses were able to provide
this information in well-structured, detailed sentences where information was linked. Students
should avoid responding in dot points for questions that ask for ‘outline’, ‘explain’, ‘describe’, etc,;
full sentences addressing the command word and that uses computing terminology are required.
The following are two examples of high-scoring responses.
Example 1
Binary search is more efficient than linear search however requires the records to be sorted. Binary search involves reducing the list by half in every step while linear search involves searching every individual record to see if it matches the desired record. With 5000 records, the average time taken to search is significantly less in binary search then linear search making it more efficient.
A binary search is a more efficient searching technique compared to a linear search. A binary search requires a sorted data set. While a linear search checks through each record, a binary search compares your wanted value with the midpoint, and discards half of the data set which is not required. This makes a binary search exponentially more efficient than a linear search.
Question 5
Marks 0 1 2 3 Average
% 62 15 14 8 0.7
There were a number of possible responses to this question; however, a number of students used
‘i’ for the counter when the variable ‘counter’ was already provided.
The following is a possible response.
While counter < array_length
If inputArray[counter] = inputArray[counter+1] then
duplicate_count duplicate_count+1
endIf
counter counter+1
endwhile
Section C – Case study
Question 1a.
Marks 0 1 2 3 4 Average
% 8 13 59 7 13 2.1
Question 1 required students to apply their knowledge of project management and utilise key terms
such as dependency, predecessor, critical path and milestones. In general, students were able to
read and interpret the tasks list and the Gantt chart. However, a number of students missed the
second part of the question, which required use of evidence from the Gantt chart. Students should
remember that answers must apply to the case study (as stated in the instructions), so responses
not related to the case study may not be awarded marks.
The following is an example of a high-scoring response.
Many tasks, including the trialling of one system, and the design of the EasyDel App are not dependent on one another, meaning they may be completed simultaneously.
The critical path is shown to only take 27 days, every task can feasibly go twice as long without the project taking 55 days.
Question 1b.
Marks 0 1 2 Average
% 12 54 34 1.2
Most students were able to describe that if the ‘Design the EasyDel app’ went longer than planned
it would impact on the project by pushing out the end date, as the task is on the critical path, thus
any delay would delay the entire project. Extending the ‘Stores to begin to add items for sale’ task
Students were asked to explain the difference between ‘includes’ and ‘extends’. An ‘explain’
question is often supported by examples; in this case it was explicitly requested in the question.
Students needed to refer to the use case diagram in their response. There was an example of both
‘includes’ and ‘extends’ in the use case diagram. In their response students should have shown
their understanding of each term and used an appropriate example to gain full marks.
The following are two examples of high-scoring responses.
Example 1
“includes” indicates that the included use case is required to complete the including use case. “make purchase” includes “customer login/registration” because the customer must be logged in to make a purchase. “extends” indicates an optional, but not required, use case that may or may not be completed while the user is performing the extended use case. “good delivery” extends “checkout” because the customer may optionally choose to have the goods delivered while they are checking out their purchase.
Example 2
The term ‘extends’ refers to an option or path that can be chosen whereas, the term ‘includes’ means that in order for a particular process to take place something else must also occur. For example, the ‘includes’ between “make purchase” and “customer login/registration” indicates that a customer must either login or register to make a purchase. In contrast, the ‘extends’ between “checkout” and “good delivery” indicates that a customer has an option when checking out for a purchase to have their good delivered to their house.
Question 4a.
Marks 0 1 Average
% 21 79 0.8
Most students were able to indicate that Bluetooth’s limited range would be the reason for rejecting
it as a means of communication with the robots.
Question 4b.
Marks 0 1 2 Average
% 59 7 34 0.8
Many students were not able to provide a technical feature. A number of responses could have
been provided, including wireless NIC or IP address. Students often used vague terms such as
‘wireless receiver/transmitter’, which was not correct technical terminology.
Question 5a.
Marks 0 1 2 3 Average
% 31 20 14 34 1.5
Students who utilised the question stem and the tests already performed provided the three key
creditnum String/Array the credit card number of the customer, 0000-0000
Question 6b.
Marks 0 1 Average
% 59 41 0.4
The type of validation was a range check as values can only be 5, 6 or 7.
Question 6c.
Marks 0 1 2 Average
% 27 35 38 1.1
creditnumtotal = 34 or 18
validcard = true
Both 34 and 18 were accepted as possible answers for creditnumtotal as the answer could be
derived using either the algorithm or its description.
Question 7a.
Marks 0 1 Average
% 92 8 0.1
Most students were not able to identify that the first line (XML declaration or prolog) of an XML file
defines its file type. The most common incorrect responses referred to the file extension.
The following is an example of a high-scoring response.
Many XML files have a header stating the version of XML. XML files also have opening and closing tags which can be used to differentiate from other files.
Question 7b.
Marks 0 1 2 Average
% 69 28 4 0.4
This question required students to apply their knowledge of XML, as XML does not deal with
formatting as such but with data and its structure. XML provides an independent way of storing and
sharing data, which means new browsers and applications can read it without losing data.
The following is an example of a high-scoring response.
XML files use self descriptive tags to describe data and give it structure. The EasyDel app can read these tags and use them to place data in the correct places.
Question 8
Marks 0 1 2 3 4 5 6 Average
% 8 5 13 25 30 14 5 3.3
Students needed to consider the words in the question ‘compare the purpose’, which required
students to discuss similarities and differences between two elements, in this case ‘backup
strategy’ and ‘data encryption’. Students then needed to recommend which should be
implemented; this recommendation could have included utilising both. Students were expected to
clearly show their knowledge of the purposes, describe the strategies and justify a
recommendation. There were a number of possible responses.
The following are two examples of high-scoring responses.
Example 1
The purpose of a back up strategy and encryption is both to increase data security. However they achieve this differently with a back up provide redundancy, allowing data to be restored if it ever gets deleted. Encryption provides security in a more traditional sense in encoding the data so that it is unreadable. To achieve best practice Lilianna should implement both of these strategies. Given that information such as credit card details is stored in the database, encryption should be considered as this information may be of high target for hackers. Furthermore, a backup should be used for redundancy to ensure that if any data is ever lost it can be restored. An incremental backup in which only data that has been changed since the last back up is backed should provide a good balance of speed and redundancy for the system.
Example 2
Data encryption is a security measure that is designed to protect data from being accessed by unauthorized users. Backup strategies such as incremental backup, where changes between any previous incremental or full backup are backed up each day, protect the company if they lose access to the data. As data encryption and backups serve different functions, one protecting security of data from attackers and another preventing data loss, it would be in Lilianna’s interests to implement both. For Lillian’s needs a daily incremental backup of the encrypted data on external hard drives, and a weekly full backup on magnetic tape (for it’s storage capacity) would be advisable.
Question 9
Marks 0 1 2 3 4 Average
% 9 15 35 23 18 2.3
Students are encouraged to read and reread the question before responding. In this question, a
number of students missed the need to explain ‘how’ the measure will help keep data secure, with
many simply describing the measure.
The following is an example of a high-scoring response.
The firewall will monitor incoming network traffic to check for unauthorised access attempts and stop them from accessing data on the server.
By encryption the signal, even if the signal is intercepted, it will be unreadable, and no useful information is gained by the intercepter, thus keeping the data secure.
Question 10a.
Marks 0 1 2 Average
% 33 45 22 0.9
The EasyDel app should include a privacy policy and the ability for the customer to agree to the
policy. Many students only included one element.
The following is an example of a high-scoring response.
The customer should be made aware of the sharing of their details when signing up for the app. This should be contained within the terms and conditions and users should be made to sign this or give consent if they sign up.
Christos must include consent to receive the emails and customers must have the ability to
unsubscribe. Many students only included one element.
The following is an example of a high-scoring response.
Customers must have given consent to be sent emails and must be able to unsubscribe from emails easily. Once a customer has unsubscribed they should no longer be sent emails.
Question 11
Marks 0 1 2 3 4 Average
% 36 27 22 10 4 1.2
A detailed description of a VPN and a considered justification for its use with the software
solution’s data was required. Many students found it difficult to include the required detail;
increased practice of detailed written responses may assist students.
The following is an example of a high-scoring response.
A VPN establishes a secured private communication channel between the storage and the RedGumGrove’s Central server. This is appropriate because outsourcing the storage necessarily requires the connection of two local area networks via the internet (that of the RedGumGroves’ and that of the storage companies). A VPN prevents unauthorised attackers from intercepting communication between the two networks.
Question 12
Marks 0 1 2 3 4 5 6 Average
% 24 9 18 11 26 7 5 2.5
Criterion Strategy Explanation
98% of customers received the items they ordered.
Classify the number of customer complaints according to the type of problem and count them.
Record the number of orders processed.
The ratio will give the percentage of customers who receive their orders.
The ratio will be used to judge if the 98 per cent criterion has been met. If over 98 per cent, then criteria successful, however if under 98 per cent criterion was not met.